Asthma is a prevalent, chronic inflammatory disease of the airways associated with a range of adverse health outcomes. Insomnia is a common complaint among those with asthma. It is often viewed as a consequence of asthma-related nocturnal awakenings, which will resolve with adequate control of asthma. Yet, our prior research suggests that insomnia persists, even in those without nighttime asthma awakenings (i.e., comorbid insomnia). Insomnia may be plausibly linked to asthma control through mechanisms such as decreased lung function and increased inflammation. Thus, targeted treatments for insomnia could be a novel approach to improving asthma control and asthma-related quality of life. The Internet is a viable option for delivery of cognitive-behavioral treatment for insomnia (CBT-I) and overcomes the limitations of face-to-face CBT-I. However, the applicability of Internet-based CBT-I for comorbid insomnia is unknown. The central hypothesis of the proposed study is that the Internet is a feasible and acceptable method to deliver CBT-I in adults with asthma and comorbid insomnia. The primary aims of the proposed study are 1) to assess the feasibility and acceptability of an Internet-based CBT-I, Sleep Healthy Using The Internet (SHUTi), in adults with asthma and comorbid insomnia and 2) to explore the need for asthma-related adaptations of SHUTi content. Focus groups will be used to obtain participants? suggestions for asthma-related or other relevant content for adaptation of the SHUTi program. The secondary aim is to explore changes in sleep and asthma outcomes from baseline to post- treatment. The use of an efficacious, low cost, Internet-based, CBT-I can provide a treatment option that could be delivered in real-world clinical settings. Study results will enable optimization of the Internet intervention and development of a clinical trial that can test the efficacy of SHUTi on sleep and asthma outcomes.